Cooperative Shared Memory and the Wisconsin Wind Tunnel

希尔，这个项目的目标是为可扩展的共享地址空间计算机设计硬件和软件。协作共享内存是项目中采用的方法，它为共享内存硬件提供了简单的设计，并提供了一个编程模型，程序员和编译器可以使用该模型来理解应用程序的通信行为。协作共享内存使用简单的目录硬件和一组用于应用程序软件的编译指示。编译指示允许应用程序软件指示哪些处理器将使用内存块：处理器可以在预期频繁使用时签出块，在完成时签入，并可以指示它希望在不久的将来签出块。可以使用简单的目录硬件将检出的内存位置放置在适当处理器的高速缓存中。目录协议中的常见状态转换在硬件中实现，而不常见的状态转换使用软件陷阱。请注意，编译指示和由此产生的硬件操作只会影响程序的执行速度，而不会影响其正确性。正在使用一种新的虚拟样机方法来评估新的架构。威斯康星州风洞在并行消息传递计算机上运行并行共享内存程序，并使用分布式模拟在拟议的硬件上同时评估程序执行时间。模拟运行得很快，因为直接执行只进行本地内存引用的指令。

Hill The goal of this project is to design hardware and software for scalable shared-address-space computers. Cooperative shared memory, the approach taken in the project, provides a simple design for shared-memory hardware and a programming model that can be used by programmers and compilers to understand an application's communication behavior. Cooperative shared memory uses simple directory hardware together with a set of pragmas for use in applications software. The pragmas allow the applications software to indicate which processors will be using a block of memory: a processor can check out a block when it expects frequent use, check it back in when it is done, and can indicate that it expects to check out a block in the near future. Simple directory hardware can be used to place checked-out-memory locations in the caches of the appropriate processors. Common state transitions in the directory protocol are implemented in hardware, while the less common ones use software traps. Note that the pragmas and the resulting hardware actions affect only the execution speed of a program, not its correctness. A new virtual prototyping approach is being used for evaluating the new architecture. The Wisconsin Wind Tunnel runs parallel shared-memory programs on a parallel message-passing computer and concurrently evaluates the programs execution times on proposed hardware using a distributed simulation. The simulation runs quickly because instructions that make only local memory references are executed directly.